But it doesn't work for me.
Please give me a clue. How to remove all images for product.
Since no one replied you yet, and in case you still need a solution, I wanted to ask if you consider extension as a solution.
If yes, you can use free version of Store Manager for Magento app (you can download it from my signature). To remove images you simply need to:
1) Select products
2) Click on bulk data clear option within the app
3) Chose to clear images
That's it. Here is the tutorial that shows how it works in action -
This way you can do the task easily and absolutely free.